NULL check before m_freem(9)

[Martin Pieuchot]

Our m_freem(9) and m_free(9) deal with NULL like free(3), so there's no need
for such checks.

ok?

Index: kern/uipc_syscalls.c
===================================================================
RCS file: /cvs/src/sys/kern/uipc_syscalls.c,v
retrieving revision 1.140
diff -u -p -r1.140 uipc_syscalls.c
--- kern/uipc_syscalls.c        21 Nov 2016 09:09:06 -0000      1.140
+++ kern/uipc_syscalls.c        28 Nov 2016 11:40:01 -0000
@@ -721,8 +721,7 @@ sendit(struct proc *p, int s, struct msg
 #endif
 bad:
        FRELE(fp, p);
-       if (to)
-               m_freem(to);
+       m_freem(to);
        return (error);
 }
 
@@ -930,10 +929,8 @@ recvit(struct proc *p, int s, struct msg
        }
 out:
        FRELE(fp, p);
-       if (from)
-               m_freem(from);
-       if (control)
-               m_freem(control);
+       m_freem(from);
+       m_freem(control);
        return (error);
 }
 
@@ -1001,8 +998,7 @@ sys_setsockopt(struct proc *p, void *v, 
        error = sosetopt(fp->f_data, SCARG(uap, level), SCARG(uap, name), m);
        m = NULL;
 bad:
-       if (m)
-               m_freem(m);
+       m_freem(m);
        FRELE(fp, p);
        return (error);
 }
@@ -1046,8 +1042,7 @@ sys_getsockopt(struct proc *p, void *v, 
        }
 out:
        FRELE(fp, p);
-       if (m != NULL)
-               (void)m_free(m);
+       m_free(m);
        return (error);
 }